The invention relates to a blade element for a refiner for refining fibrous material, the blade element comprising a refining surface, the refining surface in turn comprising blade bars and blade grooves between them.
The invention further relates to a refiner for refining fibrous material, the refiner comprising at least two refining elements positioned oppositely at a distance from one another and moving in relation to one another, the opposite surfaces of the refining elements being provided with a refining surface for refining fibrous material and that the refining surface of at least one refining element comprises blade bars and blade grooves between them.
Refiners intended for refining fibrous, lignocellulose-containing material, such as wood material, are employed, for instance, for producing pulp to be used in paper or board making. During the refining the fibers in the fibrous material are modified with the intention of acting on the properties of the bonds between fibers created in the fiber web to be formed of the pulp. The fibrous material is refined in refiners into which the fibrous material to be refined is supplied as a pulp mixture of fibrous material and water.
Refiners meant for processing fibrous material comprise two or more substantially oppositely positioned refining elements. A refiner typically comprises one fixed refining element, i.e. a stator, and a refining element rotatable in relation to the fixed refining element, i.e. a rotor. The fixed refining element is supported to the refiner frame and the rotatable refining element is coupled to a rotation motor by a shaft. The fixed refining element comprises a body and one or more blade elements attached thereto, the blade surfaces, or refining surfaces, of the blade elements together forming the refining surface of the fixed refining element. Alternatively, the fixed refining element is formed of one or more blade elements fastened directly to the refiner frame. The rotatable refining element comprises a body and one or more blade elements attached thereto, the blade surfaces, or refining surfaces, of the blade elements together forming the refining surface of the rotatable refining element.
The fixed refining element and the rotatable refining element are placed oppositely to one another and at a distance from one another, the distance forming a blade gap of the refiner. The oppositely aligned refining surfaces and the blade gap define a refining space in which the refining takes place. The refining is caused by pressing of the refining surfaces against one another and the motion between them, as a result of frictional forces between the refining surfaces and the material to be refined and, on the other hand, as a result of internal frictional forces created in the material to be refined. The size of the blade gap may vary at different points of the refining space. The fibrous material to be refined is supplied into the refining space through a supply opening, which is connected by a supply channel to a process step preceding the refining. The refined fibrous material is removed from the refining space through a discharge opening, which is connected by a discharge channel to a process step following the refining.
In other words, the refining surface of the refining element is formed of the refining surface of one blade element or the refining surfaces of a plural number of blade elements placed next to one another. The refining surface of the blade element, and hence also the refining surface of the actual refining element, comprises blade bars and blade grooves between them. The blade bars on the oppositely placed refining surfaces participate in the actual refining, whereas the blade grooves between the blade bars move the material to be refined and the material already refined onward on the refining surfaces of the refining elements.